Given the article, the more interesting question is how we react if the answer is "Yes".

For almost hundreds of reasons, if any government, but specially super-power government would have UFO's tech hidden, and everybody else is almost certain UFOs are a myth, some wacko-level talk for internet forums

They would be strategically obligued to deny everything, so the answer would "No, no such a thing like UFOs here".

i.e. what happened with the NSA programs, most were almost fully known for the "conspiracy wackos" except by the name of the program, even decades before Snowden. But just were confirmed to be real maybe 30 years after the first mentions in the 70s,80s,90s.

Alternatively, if you had access to an immense and unassailable technological advantage over everyone, wouldn't you want to leverage that? Wouldn't it be nice to tell our enemies "we don't care how many nukes you have, we can do whatever we want with impunity or else we'll use our alien tech to protect ourselves and destroy our enemies" or to tell our allies "stick with us we're gonna be rolling out a stream of inventions that will each dramatically increase our prosperity for decades to come"? You only keep your strength hidden if it could potentially be negated - i.e. that they could develop the same technology or an effective counter without having access to alien spacecraft.

You're right mostly, there are also some special cases where it makes sense to hide the UFOs (or any radically new, advanced tech), some examples:

- the alien tech isn't really and/or fully available, they are half way in the reverse engineering efforts, and maybe other powers are in the race too

- the alien tech intrinsically reveals some currently hidden aspect of the universe/reality, if you present the technology publicly, it will be obvious that there's something new, and everybody will pursuit advances related to these new physics.

i.e. imagine discovering the eletricity in the XV century, it would have changed everything.